Monte Carlo Simulation of Single-Crystalline PbSe Nanowire Thermal Conductivity Using First-Principle Phonon Properties

TL;DR

This study uses first-principle phonon properties and Monte Carlo simulations to analyze how boundary roughness affects the thermal conductivity of PbSe nanowires, revealing significant reductions at small diameters.

Contribution

It provides a first-principles based simulation of phonon-boundary scattering effects on nanowire thermal conductivity without adjustable parameters.

Findings

Thermal conductivity decreases by ~40% for 10 nm rough PbSe nanowires at room temperature.

Boundary roughness significantly impacts phonon transport in nanowires.

Diameter-dependent thermal conductivities reveal phonon mean free path distributions.

Abstract

Prior experimental studies showed that nanowires are promising structures for improving the thermoelectric performance of practical thermoelectric materials due to the strongly induced phonon-boundary scattering. However, few studies examined the impact of phonon-boundary scattering on the thermal conductivity of thermoelectric nanowires from a first-principle approach. In this work, we systematically study the role of phonon-boundary scattering with different boundary specularities on the thermal conductivity of PbSe nanowires by rigorously solving the full phonon Boltzmann transport equation without any adjustable parameters. We observe significant thermal conductivity reduction for rough PbSe nanowires with diameters less than a few hundred nanometers. The reduction reaches ~ 40% for 10 nm thick rough PbSe nanowires at room temperature. The diameter-dependent thermal conductivities are found to contain important information about the phonon mean free path distribution from a standard reconstruction algorithm. The simulation results are important for fundamental understanding of nanoscale thermal transport in thermoelectric materials and will guide future design of thermoelectric devices to achieve better energy conversion efficiency.